PCI: epf-mhi: Make use of the alignment restriction from EPF core

Instead of hardcoding the alignment restriction in the EPF_MHI driver, make
use of the info available from the EPF core that reflects the alignment
restriction of the endpoint controller.

For this purpose, let's introduce the get_align_offset() static function.

[kwilczynski: update get_align_offset() to avoid issues on 32-bit architectures]
Link: https://lore.kernel.org/linux-pci/20230717065459.14138-3-manivannan.sadhasivam@linaro.org
Link: https://lore.kernel.org/linux-pci/20230826150626.23309-1-manivannan.sadhasivam@linaro.org
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>